An Online Open-Circuit Fault Diagnosis Technique for Three-Level Inverter-Fed Six-Phase PMSM Drives

This article presents an online open-phase and open-switch fault diagnosis technique for three-level (3L) active-neutral-point-clamped (ANPC) inverter-fed six-phase permanent-magnet synchronous machine (PMSM) drives with one or two isolated neutral points. One of the main advantages of six-phase PMSM drives is their intrinsic capability to operate at a lower power level in the event of phase or power switch failures. However, for transitioning from pre- to postfault control, fault detection and fault localization techniques are required. The open-circuit faults (OCFs) are commonly detected by observing the postfault characteristics of the drive. Due to the high number of phases and active switches per phase of 3L-ANPC inverter-fed six-phase PMSM drives, OCF detection is complicated as postfault characteristics change depending on the location and type of faults. In this article, OCFs are divided into three categories depending on the location of the fault. The average line current values are used to determine the category and location of the fault. The OCF diagnosis technique is experimentally verified using a GaN-based 3L-ANPC inverter-driven six-phase PMSM prototype.